1. Field of the Invention
The invention relates to a fuse relay junction block for use in automobiles to concentratedly control electric circuits of a variety of systems in the automobiles.
2. Related Art
There has been increasing a tendency that electronic devices or electric parts are mounted on automobiles to enhance fuel economy, anti-pollution measure, drivability, comfortableness in an interior space or the like. Electric wiring systems for driving the electric parts, electronic devices are complex in an engine room or in a car. Further, there has been considerably increasing a tendency that line brakes such as fuses, relays that are used for protecting these electric parts and electronic devices from overcurrent thereof.
Fuse relay junction blocks (that is also called a fuse relay control box, a fuse relay box or a fuse relay box) are divided into and installed on two blocks of an interior electrical wiring system and an engine room electrical wiring system, and wiring systems amount to 500 to 100 and they increase every year so that the fuse relay junction block inevitably becomes large-sized and complex.
FIG. 9 shows an example of a conventional fuse relay junction block wherein wiring boards (hereinafter simply referred to as boards) 54, 55 are housed in an inner bottom of a box body 50 and a downward recess of a box cover 52. Three middle boards 56, 57 and 58 are interposed between the boards 54, 55 to form a multilayer wiring board. The fuse relay junction block attains the size of a lunch box depending on the assemblage of these boards.
Provided on the upper surface of the box cover 52 are cable connection ports 62 through which cables from a variety of electrical wiring systems are connected, mounting ports arranged in three rows in which fuses are inserted, wherein respective electrical wiring systems are connected to corresponding fuses via wiring members 68 arranged on the respective boards 54 to 58 (in the case of the boards 56 to 58, they are arranged on lower surfaces thereof).
However, the conventional fuse relay junction block has the following problems.
It takes much trouble for arranging the wiring members on the boards 54 to 58 because recessed grooves are required for engaging the wiring members in the upper or lower surfaces of the respective boards to bond and fix the wiring members onto the recessed grooves. Further since the electronic devices and electric parts are arranged that (not in three dimensions) on each surface of each board, it is necessary to prevent these wiring members from getting entangled with one another, thereby forming a multilayer wiring board, namely, forming an assemblage of many boards as shown in FIG. 9.
There is provided on each boards slits 70 through which terminals serving as input/output portions of each wiring member provided on the other board are passed and the respective boards get in contact with one another by vertically arranged wiring members respective slits 70. When assembling the boards, the terminals are required to be inserted into or passed through the slits 70, resulting in much trouble.
Further, if the member of a board increases, there arises a problem that not only the number of molding increases, but also an outside air enters between boards to cause wiring members to corrode, thereby degrading durability and reliability in safety.
Still further, conventional wiring members are fixed to boards each formed of resin or the like by the means of the thermal deposition and expose terminal ends thereof through which fuses or the like are inserted from slits of an armoring case. Accordingly, the wiring members are prone to be rickety, and hence they are required to employ a material having an excellent elasticity as conductive terminals for inserting the terminals of the fuse or the like thereinto so as to fix and hold the fuse or the like to the wiring members. Accordingly, the conventional wiring members (conductive members) employ a copper alloy material composed of Cu and small amount of other metals such as Mg, Sn, Ni, P that are added to Cu so as to have elasticity (spring back property), causing a problem of high cost of materials.
The invention has been developed to solve the foregoing problems, and it is an object of the invention to provide a fuse relay junction block for use in automobiles capable of not only considerably reducing the number of assembling process but also realizing small sized, lightweight compact block, thereby enhancing reliability and achieving a low cost material by rendering the conventional plural boards intensive or aggregating the conventional plural boards to form a multilayered circuit structure.
To achieve the above object, the invention provides the fuse relay junction block for use in automobiles comprising a box cover having a plurality of connection ports through which wirings of electronic wiring systems are connected to terminals of wiring members, and a plurality of filling ports for fuses, a box body, a multilayer wiring board housed between the box cover and the box body, wherein said wiring members being arranged on not less than two layers of board and integrated with primary molded portions by insert molding to form a network structure, said network structure is subjected to an insert to form a secondary molded portion.
With the construction of the invention, viewed from the angle of the network structure, the primary molded portions formed by the insertion molding decide not only positions between the mutual wiring members on the respective layers of board but also intervals between the mutual wiring members arranged between the respective layers of board, thereby reducing troubles involved in manually arranging the wiring members on the respective boards and involved in assembling plural boards by piling up the plural boards.
Further, it is relatively free to design wiring members on the same layer of board so that the wiring members can be crossed with one another in three dimensions on the same layer of board. Still further, since the extraction pores through which a material of the primary molded portion is filled is provided on the respective wiring members, the stability of the configuration of the network structure is maintained to easily perform a secondary molding. More still further, since the material of the wiring members are composed of pure copper, the fuse relay junction block can be manufactured at low cost in view of a material.